Board-forming machine



April 2, 1963 J. PAGE EI'AL BOARD-FORMING MACHINE 2 Sheets-Sheet 1 Filed March 50. 1959 INV NTORS. e6 2:2;

April 2, 1963 J. PAGE ETAL 3,083,756

BOARD-FORMING MACHINE Filed March so, 1959 2 Sheets-Sheet 2 United States Patent 3,083,756 BOARD-FORMING MACHINE John Page, Glenview, and Robert E. McCleary, Geneva,

IlL, assignors to United States Gypsum Company, Chicago, 111., a corporation of Illinois Filed Mar. 30, 1959, Ser. No. 802,850 Claims. (Cl. 156--345) This invention relates to a board-forming machine and more particularly to a machine employed in the continuous manufacture of gypsum core wallboard or lath.

In the manufacture of such a product, an aqueous slurry of calcined gypsum is deposited between two laminae, such as paper. In prior machines employed in the manufacture of this product, a pair of forming rolls are utilized. These rolls are spaced apart a predetermined distance, depending upon the desired thickness of the finished product. Cooperating with the lower forming roll is a bed plate over which the bottom lamina is guided before contacting the periphery of such roll. The upper surface of the bed plate is disposed in substantially tangential relation with respect to the periphery of the lower roll. Prior to the bottom lamina engaging the lower roll, an aqueous calcined gypsum slurry is deposited thereon in such an amount as to cause the slurry to dam up on the bottom lamina at the entrance to the opening between the forming rolls. The spaced-apart forming rolls permit only the necessary amount of slurry to pass therebetween to form the gypsum core of desired thickness. Simultaneously with the passing of the slurry between the forming rolls, there is fed a top lamina which cooperates with the bottom lamina to effect sandwiching of the gypsum core therebetween. Subsequent to the laminae and gypsum core passing between the forming rolls, the board is customarily conveyed away from the rolls on an endless belt for further processing; these latter processing steps constitute no part of the invention to be hereinafter described.

Because of the relatively large diameter of the lower forming roll and the pulley of the conveyor (i.e., each being approximately 16 inches), and the clearance be tween the roll and pulley, the endless belt must be spaced approximately 18 inches from the passageway between the rolls, with the result that there is provided a rather elongated gap over which the freshly formed board is caused to pass in an unsupported state, with the result that the board has a tendency to sag. An effort is made to control the amount of sag by increasing the tension on the lamina; however, this procedure is usually inefiective because the laminae become somewhat limp when they are wet. Furthermore, the benefits derived by increasing the lamina tension in attempting to correct sag are normally outweighed by the problems which result in obtaining accurate control of the thickness of the finished product.

A further difficulty which besets the prior art machines of the type aforedescribed is that the laminae are susceptible to tearing, particularly when some enlarged foreign hard substance, entrained within the slurry, attempts to pass between the forming rolls. Furthermore, because of the size of the forming rolls and their close proximity to one another, a further diificulty is oftentimes encountered in the prior art machines in endeavoring to effectively clean the passageway formed between the rolls. Lastly, in many of the prior art machines there exist many safety hazards and thus require constant care and vigilance on the part of personnel attending the machine.

Thus, it is one of the objects of this invention to provide a board-forming machine which overcomes the aforementioned shortcomings and difficulties associated with the prior art machines.

It is a further object of this invention to provide a 7 ice board-forming machine which is of simple, yet sturdy, construction, effective in operation, and embodies numerous safety features.

Further and additional objects will appear from the description, accompanying drawings, and appended claims.

In accordance with one embodiment of this invention, a board-forming machine is provided which includes an elongated substantially fiat bed plate and an elongated element spaced above a portion of the plate a finite distance. The elongated element is provided with an arcuate periphery which cooperates with the bed plate portion to form an elongated narrow passageway. The lower lamina of the board is fed across the bed plate and through the passageway in a direction transverse to the elongated axis of the element. Means are provided for depositing an aqueous calcined gypsum slurry on the bottom lamina at the entrance to the passageway in such an amount as to cause dam-up or an excessive accumulation of slurry at the entrance to the passageway. As a result of the dam-up of the slurry, only a predetermined amount thereof is permitted to pass between the periphery of the element and the portion of the bed plate subtending such element. Simultaneously with the feeding of the bottom lamina and slurry through the passageway, there is also fed a top lamina which overlies the gypsum slurry and cooperates with the bottom lamina to sandwich therebetween a core of proper thickness. The portion of the bed plate forming the passageway is adapted to retract from the surface of the remainder of the bed plate, engaged by the bottom lamina, when a predetermined force is imparted on said bed plate portion.

For a more complete understanding of the invention, reference should be made to the drawings wherein:

' FIGURE 1 is a fragmentary front elevational view of one form of the improved machine;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged fragmentary vertical sectional view showing the passageway between the roll and the bed plate;

FIG. 4 is similar to FIG. 3, but showing a modified form of the improved machine; and

FIG. 5 is a diagrammatic view of the pneumatic pressure control system.

Referring now to the drawings, an improved boardforming machine 10 is shown, which is adapted for use in the continuous formation of wallboard or lath having a gypsum core and top and bottom laminate of paper sheets. The machine 10 comprises an upright frame 11 which is adapted to support in a substantially horizontal plane an elongated bed plate 12. Over the bed plate 12 is adapted to be a fed a web of sheet material which is adapted to function as the bottom lamina 13 of the finished product. The web or lamina 13 is fed from a stock roll 14 disposed adjacent one end of the frame 11.

Mounted above the exposed surface of the bed plate 12 is either an elongated master roll 15 (see FIG. 1) or an elongated second plate 15a which has an'arcuate periphery, (see FIG. 4). The periphery of either roll 15 or plate 15a is spaced from the bed plate surf-ace a finite distance so as to form an elongated passageway 16 (see FIGS. 3 and 4), which is of predetermined size. The axis of the roll or elongated plate is disposed substantially transversely to the direction in which the web 13 is fed. The size of the passageway 16 determines the ultimate thickness of the finished product. The roll 15 is supported at its ends by bearings 17 which, in turn, are secured to the upright standards 17a. These standards form a part of frame 11. Arcuate plate 15a, on the other hand, may have one edge thereof hingedly connected to the frame, while the other edge thereof may be adjustably mounted so as to permit the size of the passageway to be varied. In FIG. 4 there is diagrammatically shown vibrators 19a and 1% which cooperate with the bed plate portion 12a and the plate 15a. If desired, however, these vibrators may be omitted, or only one used.

Disposed on the entrance side of the passageway 16 is a conduit 18 through which flows a calcined gypsum slurry which is adapted to be deposited on the exposed surface of the web 13 prior to the latter passing through passageway 16. The amount of slurry deposited on web 13 is such as to cause dam-up .thereof, or an excessive accumulation of the slurry at the entrance 21 to passageway 16. Because of the restricted size of passageway 16, only a controlled amount of the slurry is permitted to pass therethrough; this amount constitutes the gypsum core 22 of the finished product.

Simultaneously with the passage of the bottom lamina 13 and the controlled amount of slurry through passageway 16 the top lamina 23 is applied. The top lamina is fed from a stock roll 24 supported above the master roll 15 or arcuate plate 15a. The top lamina 23, in this instance, is in the form of a web of paper which, upon leaving stock roll 24, passes guide rolls 25 and then engages and conforms to a portion of the periphery of master roll 15 or plate 15a. Means are provided for adjusting the position of the master roll bearings 17 relative to the standards 17a so as to vary the size of passageway 16 and the thickness of the finished product. The arcuate plate "15a, as heretofore mentioned, is also adjustable. By reason of these facts, the utility of the machine is materially increased.

To permit passage through passageway 16 of an enlarged hard object which might have become entrained in the slurry, a portion of the bed plate 12a, which subtends roll 15 or arcuate plate 15a, is adapted to automatically yield or retract from its flush position with the upper surface of the remainder of the bed plate. Thus, by reason of this yielding, no damage Such as tearing or rupturing of the laminae, occurs. One form of accomplishing this result is illustrated in the drawings. The portion 12a is preferably of rectangular configuration and is hinged along one edge thereof by a shaft 26 a mounted on framelll. The location of shaft 26 on the frame 11 is downstream with respect to passageway 16. The plate portion 12a is controlled in its pivotal movement by piston cylinder assembly 27, the lower portion of which is hingedly connected at 28 to frame 11. The exposed end of the piston, on the other hand, is pivotally connected at 29 to the underside of bed plate portion,

2a. The piston cylinder assembly 27, in this instance, is of a pneumatic type.

The control system for assembly 2'! is shown diagrammatically in FIG. -5. The system includes a master valve 39 which is'disposed within the main air pressure line 31 of the plant in which the machine is located. Adjustment of valve is accomplished through a shuttle valve 32 which, in turn, is controlled by a plurality of remote valves3'3 and 34. Valve 33, in this instance, is a safety valve and is located above the entrance to passageway 16. Valve 33 includes an elongated bar 33a which is substantially the width of the bed plate 12. When valve 33 is depressed, shuttle valve 32 is actuated, causing master valve 30, in turn, to release the air pressure within cylinder assembly 27, whereupon plate portion'12a will fall by its own weight to position A, shown in dotted lines in FIG. 1.

Valve 34, on the other hand, is located alongside the bed plate 12 and also causes pressure within cylinder assembly 2'7 to be released. The principal distinction between halves 33 and 34- is that the former shuts down the entire line, that is to say, the conveyor system, as well, to be hereinafter discussed. Thus, with valves 33 and 34 being provided, an important safety feature is incorporated in the machine which avoids serious injury i to the operator in the event a part of his clothing or his arm accidentally gets caught in passageway 16. Also, having plate portion retractable to position A facilitates cleaning of the passageway.

Included in the control system is a valve mechanism 35 which is placed in line 31 ahead of master valve 30 (see FIG. 5). The function of mechanism 35 is to adjust the pressure to be maintained within assembly 27, so that the latter will support plate portion 12a in a fiush position 3 with respect to the remainder of the bed plate. The pressure, therefore, within assembly 27 must be slightly in excess of the combined weight of the portion 12a and the board resting thereupon, so as to enable the plate portion 12a to yield due to the added pressure caused by the passage of the hard object through passageway 16. To permit plate portion 12a to assume a proper flush position B, an adjustable screw 36 is carried on the edge of the plate portion 12a opposite the hinged edge thereof. Screw 36 contacts the underside of the remainder of the bed plate 12. If desired, an electrical contact, not shown, may be utilized between the screw 36 and bed plate 12 to indicate when the portion 12a is properly in position B. Such an electrical contact may, in turn, be connected to a signal light, not shown.

While plate portion 12a has been described as being hinged to the remainder of the bed plate 12, it is to be understood, of course, that other means may be employed to effect retraction of such portion and, therefore, the invention is not limited to the precise construction shown and described.

Mounted adjacent the shaft 26, and in as close proximity thereto as possible, is a pulley 37 about which a conveyor belt 38 is mounted. The conveyor belt 38 has the upper segment thereof substantially coplanar with the bed plate surface whereby the board, subsequent to forming, will be readily fed onto the conveyor belt and then moved away from the master forming roll 15 or plate 15a. Because of the close proximity of the pulley 37 to the shaft 25, there is a relatively narrow gap 39 created, over which the formed board passes in an unsupported condition. Thus, the possibility of the board having a tendency to sag at this point is materially reduced, if not entirely eliminated.

If desired, scoring cutters 40 may be mounted on the frame 11 adjacent stock roll 14. Such cutters 40 are utilized for imparting score lines to the bottom lamina 13. These cutters 40', however, may be eliminated, if desired.

Thus, it will be seen that a board-forming machine has been provided which is possessed of an effective safety feature and, in addition, enables ready cleaning of the master forming roll, as well as the bed plate surface. In addition, the improved machine is adapted to form boards of various thicknesses. The possibility of sagging of the board, subsequent to the forming thereof, has also been materially reduced, or entirely eliminated.

While a particular embodiment of this invention has been shown, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

We claim:

1. A machine for forming board having a gypsum core, and bottom and top laminae of fibrous material, said machine comprising a continuous board-forming first section and 1a board-conveying second section adjacent said first section for effecting continuous removal of board from said forming section; said forming section comprising a bed plate, an elongated element spaced above said plate, the periphery of said element being arcuate and cooperating with said plate to form an elongated narrow passageway the length of said element, the portion of said plate disposed beneath said element and forming said passageway being retractable relative to the remainder of said plate; means mounting said portion of said plate for selective retraction from said element; means for feeding the bottom lamina over said bed plate and through said passageway in a direction substantially transverse to the axis of said element; means for depositing a calcined gypsum slurry on the bottom lamina at the entrance to said passageway; and means cooperating with said element for feeding the top lamina through said passageway whereby a gypsum core of predetermined thickness is formed between the laminae; said second section comprising elongated movable means having a receiving end thereof adjacent the passagewayforrning peripheral segment of said element, said receiving end being disposed in substantially coplanar relation with said bed plate.

2. A machine for forming board having a gypsum core, and bottom and top laminae of fibrous material, said machine comprising a substantially flat bed plate over which the bottom lamina is moved in one direction, an elongated element spaced above said bed plate, the periphery of said element cooperating with said plate to form an elongated narrow passageway the length of said element through which such bottom lamina is caused to pass, the portion of said plate disposed beneath said element and forming said passageway being retractable relative to the remainder of said plate, means mounting said portion of said plate for selective retraction from said element, means for depositing a calcined gypsum slurry on such bottom lamina at the entrance to said passageway; and means cooperating with said element to effect feeding of a top lamina through said passageway, whereby a gypsum core of predetermined thickness is formed between the laminae within said passageway and said passageway may be enlarged by retracting said passagewayiorming portion of said plate.

3. The machine recited in claim 2, and wherein said means mounting said portion includes a yielda-ble means connected to said plate portion to effect automatic retraction of said plate portion upon a predetermined downward force being exerted thereon.

4. The machine recited in claim 3 wherein said yieldablc means comprises a hydraulically actuated piston and cylinder assembly.

5. A machine for forming board having a gypsum core and bottom and top laminae of fibrous material, said machine comprising a substantially fiat bed member, an elongated element spaced from said bed member and having the periphery thereof :arcuate and opposed to a portion of said bed member to form an elongated narrow passageway extending the length of said element and substantially the full width of said bed member, said portion of said bed member opposite said element and forming said passageway being movable independently of the remainder of said bed member in a direction away from the periphery of said element, means yieldably supporting said portion for such movement, means for feeding said laminae through said passageway, means for depositing -a calcined gypsum slurry between said laminae on the entrance side of said passageway, whereby a gypsum core of predetermined thickness is normally formed between the laminae; said means yiel-dably supporting said portion of said bed member exerting a predetermined pressure against said plate in the direction of said elongated element, said passageway being automatically enlarged by exertion of a force in excess of said predetermined pressure on said portion of said. bed member in a direction away from said element.

References Cited in the file of this patent UNITED STATES PATENTS 1,455,1 27 Utzman May 15, 1923 1,837,381 Turner Dec. Z2, 1931 2,200,155 Camp et a1. May 7, 1940 2,380,527 Hoggatt July 31, 1945 FOREIGN PATENTS 118,395 Great Britain Aug. 29, 1918 

1. A MACHINE FOR FORMING BOARD HAVING A GYPSUM CORE, AND BOTTOM AND TOP LAMINAE OF FIBROUS MATERIAL, SAID MACHINE COMPRISING A CONTINUOUS BOARD-FORMING FIRST SECTION AND A BOARD-CONVEYING SECOND SECTION ADJACENT SAID FIRST SECTION FOR EFFECTING CONTINUOUS REMOVAL OF BOARD FROM SAID FORMING SECTION; SAID FORMING SECTION COMPRISING A BED PLATE, AN ELONGATED ELEMENT SPACED ABOVE SAID PLATE, THE PERIPHERY OF SAID ELEMENT BEING ARCUATE AND COOPERATING WITH SAID PLATE TO FORM AN ELONGATED NARROW PASSAGEWAY THE LENGTH OF SAID ELEMENT, THE PORTION OF SAID PLATE DISPOSED BENEATH SAID ELEMENT AND FORMING SAID PASSAGEWAY BEING RETRACTABLE RELATIVE TO THE REMAINDER OF SAID PLATE; MEANS MOUNTING SAID PORTION OF SAID PLATE FOR SELECTIVE RETRACTION FROM SAID ELEMENT; MEANS FOR FEEDING THE BOTTOM LAMINA OVER SAID BED PLATE AND THROUGH SAID PASSAGEWAY IN A DIRECTION SUBSTANTIALLY TRANSVERSE TO THE AXIS OF SAID ELEMENT; MEANS FOR DEPOSITING A CALCINED GYPSUM SLURRY ON THE BOTTOM LAMINA AT THE ENTRANCE TO SAID PASSAGEWAY; AND MEANS COOPERATING WITH SAID ELEMENT FOR FEEDING THE TOP LAMINA THROUGH SAID PASSAGEWAY WHEREBY A GYPSUM CORE OF PREDETERMINED THICKNESS IS FORMED BETWEEN THE LAMINAE; SAID SECOND SECTION COMPRISING ELONGATED MOVABLE MEANS HAVING A RECEIVING END THEREOF ADJACENT THE PASSAGEWAYFORMING PERIPHERAL SEGMENT OF SAID ELEMENT, SAID RECEIVING END BEING DISPOSED IN SUBSTANTIALLY COPLANAR RELATION WITH SAID BED PLATE, 